Phosphorus Analogues of Diazonium Ions. Stabilities, Spectroscopic Properties, and Electronic Structures of the P Analogues of Methyldiazonium Ion

Author

Rainer Glaser, Missouri University of Science and TechnologyFollow
Christopher J. Horan
Godwin Sik Cheung Choy
Benjamin L. Harris

Abstract

The P analogues of methyldiazonium ion (CH₃NN)⁺ (1), methyldiphosphonium ion (CH₃PP)⁺ (2), methylphosphoazonium ion (CH₃NP)⁺ (3), and methylazophosphonium ion (CH₃PN)⁺ (4) were studied with ab initio techniques. Potential energy surface analysis shows that the C_3v-symmetric ions all are minima. 4 corresponds to a shallow minimum along the automerization path of its isomer 3. A bridged structure of 2 exists as a local minimum along the automerization path, and this automerization occurs within a tightly bonded ion-molecule complex with small activation barriers. Methyl cation affinities of 43.0, 71.3, 100.4, and 42.1 kcal/mol were determined for the formations of 1-4, respectively, at MP4(fc,sdtq)/6-31 lG(df,p)//MP2- (full)/6-31 lG(df,p) and including MP2(full)/6-31G(d) vibrational zero-point energies. The thermodynamic stabilities of 2 and 3 with regard to the dissociations (CH₃XY)⁺ → CH₃⁺ + XY might be affected by exothermic XY oligomerization and the reactions (CH₃PP)⁺ → CH₃⁺ + ½P₄ and (CH₃NP)⁺ → CH₃⁺ + ⅓D_3h(PN)₃ were studied. Ions 2 and 3 are predicted to be more stable toward dissociation than 1. These results suggest that 2 and 3 should be detectable in the gas phase and possibly also in superacidic media. Like its aryl analogue, 3 might be accessible synthetically. Spectroscopic properties including IR spectra, dipole and quadrupole moments, rotational constants, and polarizabilities are reported that may assist in their detection. Electronic structures of 1-4 were studied in a variety of ways. A new energy decomposition method related to the definition of the electron density difference function, Δρ = ρ (CH₃XY⁺) - ρ^M(CH₃⁺) - ρ^M(XY), is presented. Charge distributions in 1-4 are discussed with regard to the Lewis notations. CN- and CP-bonded ions clearly show distinct bonding patterns.

Recommended Citation

R. Glaser et al., "Phosphorus Analogues of Diazonium Ions. Stabilities, Spectroscopic Properties, and Electronic Structures of the P Analogues of Methyldiazonium Ion," Journal of Physical Chemistry, vol. 96, no. 9, pp. 3689 - 3697, American Chemical Society (ACS), Apr 1992.

The definitive version is available at https://doi.org/10.1021/j100188a025

Department(s)

Chemistry

International Standard Serial Number (ISSN)

0022-3654

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1992 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Apr 1992